DSC,ESR, IR, Raman, optical absorption and dc conductivity studies on10Li2O- xNb2O5-(89-x) TeO2 glasses containing Cu2+ spin probe have been carried out. Glass transition temperature (Tg) and thermal stability of glass samples are estimated from the DSC measurements and it has been found that both increase with increasing the Nb2O5 content. From IR and Raman spectra, it is clear that, the glass system consists of structural units of TeO3 (tp), TeO4 (tbp) and NbO6 octahedra. TeO4 units are found to be converted into TeO3 units with increase in Nb2O5 content. From ESR spectra, it is found that the Cu2+ ion is in tetragonal distorted octahedral site with dx2-y2 as ground state. The observed optical absorption peak of Cu2+ is found to be maximum at 800 nm for 10 mol % of Nb2O5 content. Bonding parameters and per cent bonding symmetry are calculated from both optical and ESR data and are found to change with increase in Nb2O5 content. The observed dc conductivity is found to be increasing with temperature and decreasing with increase in Nb2O5 content.

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